\subsection{Emulator}
\label{sec:emulator}

The initial idea was to use the intercepted UID on an existing NFC card, this is not possible however as UIDs are set by the manufacturer as read-only data \cite{NXP:Classic1K}. Smartphones running the latest version of Android support a feature called Host-based Card Emulation which looked attractive. However as a UID is randomly generated each time and can't be specified it was insufficient for the goals of this project.

The remaining option was to create a circuit to emulate an NFC card as seen in \cref{fig:emulator}. Prior work was done by Nicolas Kruse \cite{Nonan:SimpleNFC} which could be adapted for the purposes of this project by changing the card-type and UID fields in the accompanying software.

\begin{figure}[ht!]
	\centering
	\includegraphics[keepaspectratio,width=0.8\textwidth]{assets/emulator.jpg}
	\caption{A working emulator that can be programmed with an intercepted UID}
	\label{fig:emulator}
\end{figure}